The statement that best explains the role of slavery in Texas's decision to secede from the Union is:
Slavery was an important part of the Texas economy, and the fear of abolition caused Texas to secede from the Union.
This reflects the significant economic reliance on slavery in Texas, as well as the prevailing fear among slaveholding states that their way of life and economic interests were threatened by the growing anti-slavery sentiment in the North and the potential for abolition.